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Wind

Materials Challenges in Present and Future Wind Energy

Brian Hayman^a1, Jakob Wedel-Heinen^a2 and Povl Brøndsted^a3

^a1 Det Norske Veritas AS and University of Oslo, Norway

^a2 Det Norske Veritas, Danmark A/S, Denmark

^a3 Risø-DTU, National Laboratory for Sustainable Energy, The Technical University of Denmark, Denmark

Abstract

The main concept currently in use in wind energy involves horizontal-axis wind turbines with blades of fiber composite materials. This turbine concept is expected to remain as the major provider of wind power in the foreseeable future. However, turbine sizes are increasing, and installation offshore means that wind turbines will be exposed to more demanding environmental conditions. Many challenges are posed by the use of fiber composites in increasingly large blades and increasingly hostile environments. Among these are achieving adequate stiffness to prevent excessive blade deflection, preventing buckling failure, ensuring adequate fatigue life under variable wind loading combined with gravitational loading, and minimizing the occurrence and consequences of production defects. A major challenge is to develop cost-effective ways to ensure that production defects do not cause unacceptable reductions in equipment strength and lifetime, given that inspection of large wind power structures is often problematic.

Brian Hayman can be reached at Section for Structural Integrity and Laboratories, Det Norske Veritas AS, NO-1322 Høvik, Norway; tel. +47–67–57–74–17, fax +47–67–57–99–11, and e-mail Brian.Hayman@dnv.com.

Hayman is a senior principal engineer in the Section for Structural Integrity and Laboratories at Det Norske Veritas in Oslo. He received his PhD degree in structural engineering at University College London in 1970. Hayman joined Det Norske Veritas in 1984. He also is an adjunct professor of mechanics in the Department of Mathematics at the University of Oslo, and assists with teaching and supervision at the Technical University of Denmark. Hayman has extensive experience with research and consultancy services in ship and offshore structures. Recently, he has been responsible for a series of research projects concerning material, structural, and joining technologies, with emphasis on lightweight structures-particularly sandwich composites.

Jakob Wedel-Heinen can be reached at Det Norske Veritas, Danmark A/S, Tuborg Parkvej 8, 2nd Floor, DK-2900 Hellerup, Denmark; tel. +45–39–45–48–54, fax +45–39–45–48–01, and e-mail jakob.wedel-heinen@dnv.com.

Wedel-Heinen has worked at Det Norske Veritas in the certifcation of wind turbine blades for more than 15 years. He received his PhD degree from the Technical University of Denmark (DTU) in 1990. Wedel-Heinen then spent two years as a postdoctoral fellow at DTU, researching composite structures. Afterward, he joined Det Norske Veritas in 1992 to work with the certifcation of wind turbines and offshore structures.

Povl Brøndsted can be reached at Materials Research Department, Risø-DTU, National Laboratory for Sustainable Energy, The Technical University of Denmark, AFM-228, PO Box 49, Fredriksborgvej 399, DK-4000 Roskilde, Denmark; tel. +45–46–77–57–04, fax +45–46–77–57–58, and e-mail povl.brondsted@risoe.dk.

Brøndsted has been head of the research program on composites and material mechanics at Risø-DTU since 2000. He earned his PhD degree from the Technical University of Denmark (DTU) in 1977. During his PhD degree study and after graduation, Brøndsted was employed in the Material Research Department at Risø National Laboratory (RNL). His research at RNL included mechanical behavior, fatigue, and fracture mechanics of metals and composite materials. Brøndsted joined the frst teams to qualify and design wind power turbines in 1976.